Automatic Online Defective Elements-Checking-and-Removing Device for Flexographic Printing Presses

ABSTRACT

The invention of automatic online defective elements checking and removing device relates to flexographic printing presses. Between a first vacuum conveying platform and a second vacuum and separating-conveying platform on the top of a mobile frame is provided a defective elements remover including a defective removing air ejector operated by a valve, which receives output signal from the online computerized visual QC station at the flexographic printing press and a receiver for carrying the ejected elements away from the platforms. Under the mobile frame is provided a vacuum pump and vacuum distribution tube connected each other with steel wire enforced hose and a ball valve is used to adjust the vacuum in order to prevent the printed labels from drifting on the conveyor belts. Both of the platforms are separately driven by motors and via toothed belts.

TECHNICAL FIELD

The invention of automatic online checking-and-removing device for defective printed elements and relates to flexographic printing presses currently used in printing industry, adding the function of automatic detection and ejection of defective printed elements such as labels. The invention could be classified into the constructional technology of printing equipment.

TECHNICAL BACKGROUND

Developing with today's advanced science and technology, the printing industry has entered digital age. However, many small and medium-sized printing workshops are still in a transitive stage between the primitive and the modern production process, with the inspection of printed products and defects ejection still stuck in the traditional stage of operators' visual check and manual removal, which needs lot of manpower and time, but still inspection mistakes occur frequently. New approaches are being explored to ensure product quality, reduce defective printed elements, improve efficiency and save manpower.

SUMMARY OF THE INVENTION

The purpose of this invention is to offer a more reliable and easily operated function for flexographic printing press, after being installed the automatic online defective elements removing device. It applies to the flexographic printing machine for labels after cutting or cutting the labels.

According to the invention there is provided, in a flexographic printing press, an automatic online defective elements checking and removing device comprising:

two stages of vacuum-conveying platform including a first vacuum-conveying platform and a second vacuum and separating-conveying platform;

both of the platforms being mounted on top of a mobile frame;

each of the platforms being separately driven by a respective motor;

a defective element remover located between the first vacuum conveying platform and the second vacuum and separating conveying platform;

a defective removing air ejector operated by a valve;

an online computerized visual QC station at the flexographic printing press arranged such that detection of a defective element causes operation of the air ejector;

a vacuum pump and vacuum distribution tube on the mobile frame;

and a valve to adjust the vacuum to the platforms in order to prevent the printed labels from moving on the conveyor belt.

Preferably there are four universal casters under the mobile frame.

Preferably there are screw bolts for adjusting the height to stabilize the frame.

Preferably the second stage includes a plurality of belts for transporting the QC passed labels. Preferably a gap between belts widens from start to end, making gaps between lines of labels during transport on the belts, facilitating the process of collection, counting, packing and stacking.

A vacuum chamber is located beneath the first vacuum conveying platform and the second vacuum conveying platform which includes the separating-conveying flat belts.

The separating conveyer belt which may comprise one to three flat belts side by side on the second stage, transports at the same time the QC passed labels.

Preferably the vacuum pump and vacuum distribution tube are connected each other with steel wire reinforced hose.

Preferably a ball valve is used to adjust the vacuum in order to prevent the printed labels from moving on the conveyor belt.

In conclusion, this invention is to reduce defects and maximize quality products. The invention is to help operators find and handle defects in time, thus raise the Quality Control (QC) pass rate, save materials, manpower, space, time and financial investment.

BRIEF DESCRIPTION OF THE DRAWINGS

On embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

Description of the attached figures

FIG. 1 is a side elevational view of one embodiment of the invention.

FIG. 2 is a top plan view of the embodiment of FIG. 1.

DETAILED DESCRIPTION

The reference numerals used in this specification are as follows:

1, movable frame;

2, vacuum distributing tube;

3, air pump;

4, the vacuum and separating conveyor platform at the second stage;

5, defective elements ejector and collector;

6, the vacuum and transporting conveyor platform at the first stage;

7, defective elements removing air ejector;

8, synchronous toothed belt;

9, asynchronous motor at the first stage;

10, asynchronous motor at the first stage;

11, universal castors;

12, screw bolt foot;

13, flat belt of the vacuum and separating conveyor platform at the second stage;

20, QC defect detector;

21, schematic illustration of flexographic printing press.

Referring to FIG. 1, there is provided in a flexographic printing machine shown schematically at 21 an automatic online defective elements removing device which comprises two stages, that is, the first vacuum-conveying platform 6 and the second vacuum and separating-conveying platform 4, both on the top of a mobile frame 1, separately driven by motors 9 and 10 via toothed belts. The defective elements collector 5 is located between the first vacuum conveying platform 6 and the second vacuum and separating conveying platform 4. The defective removing collection system includes the collector 5 which carries the labels downwardly into a collection container and an air ejector 7 which is operated by a valve in response to an output signal from an online computerized visual QC station 20 at the flexographic printing press 21 which acts to detect defective printed elements.

Under the mobile rack 1 is installed a vacuum pump 3 and vacuum distribution tube 2 connected to each other by steel wire reinforced hose. A ball valve is used to adjust the vacuum in the conveyors 4 and 6 in order to prevent the printed labels from moving from their positions on the conveyor belt.

The mobile frame at the bottom has four universal casters 11 for easy online and offline combination. There are provided screw bolts 12 for adjusting the height to stabilize the rack.

The second stage 4 includes between one and three flat belts 13 at transversely spaced positions arranged to transport at the same time QC passed labels. The gap between belts 13 widens from start to end, making gaps between the lines of labels during transport on the belts, facilitating the process of collection, counting, packing and stacking at the end of the conveyor stage 4.

The flexographic printing press equipped with the online automatic defective elements checking and removing device operates as follows.

A computerized inspection unit is installed at the flexographic printing press (not shown upstream of the first stage 6) and this checks on line the quality of the printed labels using conventional optical analysis thereof. Once a defective label is detected, the unit reports its position, outputs an alarm, and gives command to the air ejector 7, which afterwards blows the defective label down into the collector 5 which includes slots 5A and transfer duct 5B. QC passed labels go straight to the vacuum and separating conveyor belts 13, from which they are delivered to a delivery table for gap forming, collecting, counting and packing.

The invention may provide the following advantages.

By means of the two key points of online QC inspection and defective elements removal, the invention is to help operators find and handle the current and potential defects in time, thus raise the QC pass rate, save materials, manpower, space, time and money. The online inspection and defective element remover has proved more powerful than 10 to 15 workers by visual check and manual selection.

In one example of application to further illustrate the invention, the QC defective elements removing device is installed at a flexographic printing press. On the top of the movable frame 1, there are the first stage vacuum transporting platform 6 and the second stage vacuum separating platform 4, driven via synchronous toothed belts by motor 9 and 10. Defective element removing device 5 is located between the first stage vacuum transporting platform 6 and the second stage vacuum separating platform 4. The defective ejecting air knife 7 is controlled by a magnetic valve which receives command from the computerized QC and visual inspection station installed at the flexographic printing press. Under the frame 1, there are air pump 3, vacuum distribution tube 2, with steel wire enforced hose linked, and further to the vacuum chambers for the first stage vacuum transporting platform 6 and the second stage vacuum separating platform 4. A ball valve is used to adjust the vacuum to prevent labels from moving on the conveyors.

For the purpose of easy online or offline installation, four universal casters, 11, are installed under the movable frame and four screw bolts are used to adjust height to stabilize the framework.

The flat belts 13 on the second stage vacuum separating platform transport 4 feed QC passed labels side by side to _(t)he delivery table for collecting, counting and packing.

Quality inspection of printed labels is performed by means of machine vision, that is computerized visualization or image analysis. Labels are scanned and digital image signals are attained via photo electric technology. The image is transmitted to a professional image processor where its features like pixel, brightness, color are analyzed and appraised. Action is taken according to the judgment. This computerized visual quality inspection has the advantage of non-contact, high speed, and vast storage of information. It gets smaller but more intelligent with the development of computer technology.

Defect detection includes omission, dirty dots, broken words, white dots, mis-registration, etc.

Defect grading is step-less, QC pass standard is set on the computer screen by simply dragging a scroll bar.

Defect displaying is time real, including pictures, size, and position.

Defect recording: millions of images can be stored for defective picture, position and size.

Hereunder briefly describe working principle of typical machine visual inspection and defect elimination device.

Light source to target, to lens, to camera, to image collector, to image processor, to signal output, to act and alarm (relay excited, valve energized, air ejector worked, and defects blown down).

Suitable computerized QC inspection stations are available from a number of professional manufacturers where the configuration of various grades is to be determined according to the quality requirements and economic investment.

The application of this invention could greatly improve quality, save manpower and space, at the same time, prevent check omission or mistakes. 

1. In a flexographic printing presses an automatic online defective elements checking and removing device comprising: two stages of vacuum-conveying platform including a first vacuum-conveying platform and a second vacuum and separating-conveying platform; both of the platforms being mounted on top of a mobile frame; each of the platforms being separately driven by a respective motor; a defective element remover located between the first vacuum conveying platform and the second vacuum and separating conveying platform; a defective removing air ejector operated by a valve; an online computerized visual QC station at the flexographic printing press arranged such that detection of a defective element causes operation of the air ejector; a vacuum pump and vacuum distribution tube on the mobile frame; and a valve to adjust the vacuum to the platforms in order to prevent the printed labels from moving on the conveyor belt.
 2. The device according to claim 1 wherein there are four universal casters under the mobile frame.
 3. The device according to claim 1 wherein there are screw bolts for adjusting the height to stabilize the frame.
 4. The device according to claim 1 wherein the second stage includes a plurality of belts for transporting the QC passed labels.
 5. The device according to claim 4 wherein a gap between belts widens from start to end, making gaps between lines of labels during transport on the belts, facilitating the process of collection, counting, packing and stacking.
 6. The device according to claim 1 wherein the vacuum pump and vacuum distribution tube are connected each other with steel wire reinforced hose.
 7. The device according to claim 1 wherein a ball valve is used to adjust the vacuum in order to prevent the printed labels from moving on _(t)he conveyor belt. 